In an image forming device such as an electrophotographic device and an electrostatic recording device, first, an electrostatic latent image formed on the photoconductor is developed with a toner. Next, as needed, a toner image thus formed is transferred onto a transfer material such as a paper sheet and then fixed thereon by various methods such as heating, pressing or solvent vapor. In the field of such an image forming device, a digital full-color copying machine and a digital full-color printer have been put to practical use. A digital full-color copying machine produces a full-color image as follows. First, an original color image is subjected to color separation with blue, green and red filters; an electrostatic latent image corresponding to the original color image, which is composed of dots that are 20 to 70 μm in diameter, is developed with yellow, magenta, cyan and black toners; and a full-color image is formed using the subtractive color mixing effect.
Recently, there is an increasing demand for full-color images with high image quality and high resolution. Especially, to increase color reproducibility, it is hoped that an image can be printed in the same hue as ink printing. For a magenta toner, a quinacridone pigment, a thioindigo pigment, a xanthene pigment, a monoazo pigment, a perylene pigment, a diketo pyrrolo pyrrole pigment or the like are used solely or mixed to use. Of these, a combination use of the quinacridone pigment with the other magenta pigment is investigated in the viewpoint of excellent weather resistance, thermal resistance and transparency.
Patent Literature 1 offers a magenta toner in which the quinacridone pigment is used in combination with the monoazo pigment, and discloses, in Examples, toners containing C.I. Pigment Red 122, C.I. Pigment Red 19 and C.I. Pigment Red 185.
Patent Literature 2 offers a magenta toner in which the quinacridone pigment is added to the monoazo pigment, and discloses, in Examples, toners containing C.I. Pigment Red 146 and C.I. Pigment Red 122.
In addition to the combination use among magenta pigments, an example of attempt to improve toner properties by combining a magenta pigment and a magenta dye is known.
Patent Literature 3 discloses a magenta toner containing C.I. Pigment Red 122 and an oily dye. Patent Literature 3 describes that a magenta toner with a wide range of color space, an excellent color reproducibility and an excellent transparency can be obtained by mixing these colorants in a specific ratio.